Technical Field
The present invention relates to a pressure compensation device and, more particularly, to a pressure compensation device applied in order to secure the air permeability of an electronic control unit (hereinafter referred to as an “ECU”) on which an electronic control element for electrically controlling the parts of a vehicle has been mounted and an ECU module including the pressure compensation device.
Description of the Related Art
In general, an ECU for electronically controlling various devices is mounted on a vehicle. The ECU receives information from sensors or switches installed in the parts of a vehicle, and it performs a variety of types of electronic control for optimizing vehicle performance and improving ride comfort and safety or providing various types of convenience to a driver and a passenger by processing the received information.
For example, an ECU for electronically controlling the operations of the engine, automatic transmission, and ABS of a vehicle functions to electronically control all the parts of a vehicle, such as a driving system, a brake system, and a steering system in addition to control of an automatic transmission in line with the development of vehicle and computer performance.
A conventional ECU applied to a vehicle includes a case configured to have a receipt space formed in the case and a PCB configured to be inserted into the case and further includes a connector coupled with the front end of the PCB for electrical connection with the vehicle side. The case may include a cover and a base and is assembled in such a way as to surround the PCB.
The ECU has high-integrated control circuit means and thus has a possibility that it may be subject to a fatal malfunction if external moisture or an alien substance is introduced into the ECU or if the ECU is overheated or internal pressure of the ECU rises due to heat generated when a circuit is driven. For this reason, the ECU must have a construction capable of satisfying air permeability against the outside while maintaining a high degree of sealing.
Japanese Patent Application Publication No. 2008-078506 in which a vent hole is formed in a case for receiving a PCB and a stopper type filter having a flow passage is installed in the vent hole and Japanese Patent Application Publication No. 2008-055981 in which a vent hole is formed in a case and the vent hole is covered with a filter film using an adhesion sheet were suggested as conventional arts for securing air permeability against the outside.
The stopper type disclosed in Japanese Patent Application Publication No. 2008-078506 has an effective structure capable of satisfying both air permeability and sealing, but it is low in competitiveness in terms of product mass productivity and a production cost because the stopper type requires an additional assembly process because a separate pressure compensation device, such as the stopper type filter, is used and a cost rises.
In contrast, the sheet type disclosed in Japanese Patent Application Publication No. 2008-055981 is advantageous in that it can simplify the assembly process and reduce a production cost because it has a simple construction compared to Japanese Patent Application Publication No. 2008-078506, but is problematic in that it does not satisfy a waterproof property against high-pressure spray corresponding to International Protection (IP) 9K in the classification of IEC Standard 60529.